A solar power generating device that converts sunlight to heat and generates power using the resultant heat has been known. In this device, sunlight is collected by a light collecting part. A heating medium (such as oil, dissolved salt, or dissolved sodium) in either or both of a container and a flow path is heated with the collected sunlight. Then, a power generator uses the heat energy of the heated heating medium to generate power. Thus, in terms of enhancing efficiency in converting sunlight to heat (that leads to enhancement of power generation efficiency), forming a member such as a member converting sunlight to heat (hereinafter called a sunlight-to-heat converting member) on a surface of either or both of the container and the flow path and facilitating heating of the heating medium with sunlight collected by the sunlight-to-heat converting member has been examined.
For example, patent document 1 suggests using a cermet layer as the sunlight-to-heat converting member. The cermet mentioned herein is a material combining ceramic and metal.
Patent document 2 suggests using a sheet material as the sunlight-to-heat converting member provided with selective coating on one side and radioactive coating on the opposite side.